TITANIUM COPPER FOR ELECTRONIC COMPONENTS

Description

[Technical Field]

[0001] The present invention is related to a titanium copper for electronic components which is suitable for electronic components, particularly connectors, battery terminals, jacks, relays, switches, autofocus camera modules, lead frames, and a method for manufacturing the titanium copper.

[Background Art]

[0002] In recent years, the miniaturization of electronic components such as lead frames, connectors which are used in electrical or electronic equipment and in-vehicle parts, has progressed, and there is a remarkable trend toward narrow pitch and low height for copper alloy members constituting electronic components. The smaller the connector is, the smaller the pin width is, and the smaller the folded work shape is. Therefore, the copper alloy members are required to have high strength to obtain the necessary spring characteristics. In this regard, a copper alloy containing titanium (hereinafter referred to as "titanium copper") has a relatively high strength and is excellent in stress relaxation characteristics among copper alloys. Therefore, titanium copper has been used for a long time as a material for signal terminals, whose strength is particularly required.

[0003] Titanium copper is an age hardening type copper alloy. When a supersaturated solid solution of Ti (which is a solute atom) is formed by the solution heat treatment, and heat treatment for a relatively long time at a low temperature is performed from this state, a modulation structure, in which the Ti concentration in the parent phase fluctuates periodically, develops and results into improvement of strengthen, because of spinodal decomposition. In the case, the problem is that the strength and the bending workability are contradictory properties. That is, if the strength is increased, the bending workability is impaired, and on the contrary, when emphasis is placed on the bending workability, the desired strength can not be obtained. In general, the higher the reduction ratio of cold rolling is, the larger the introduced amount of dislocation is, and the higher the dislocation density is. And thus, the number of nucleation sites contributing to precipitation increases, and the strength after aging treatment can be increased. However, when the reduction ratio is too high, the bending workability deteriorates. For This reason, it has been a problem to achieve both strength and bending workability.

[0004]  Under this circumstance, Patent Document 1 (JP2013-100586A) discloses a titanium copper comprising Ti of 1.5 to 5.0 mass%, and the rest consisting of copper and inevitable impurities, having a tensile strength of 800 MPa or more, wherein when an EBSD measurement is carried out parallel to the plate thickness direction at the central portion in the plate thickness direction which is a cross sectional position of 45 to 55% with respect to the thickness, and when the crystal orientation is analyzed, the area ratio of Cube orientation {001} <100> Is 5% or more, the area ratio of Brass orientation {110} <112> is 40% or less, and the area ratio of Copper orientation {112} <111> is 20% or less. According to this disclosure, by controlling the crystal orientation inside the copper alloy plate in this way, it is possible to obtain sufficient bending workability for notch bending.

[0005] Further, Patent Document 2 (WO2012/029717) discloses a copper alloy sheet material containing 1.0 to 5.0 mass% of Ti and the rest consisting of copper and inevitable impurities, wherein in the crystal orientation analysis by EBSD measurement, the copper alloy sheet material is characterized in that the area ratio of the Cube orientation {001} <100> is 5 to 50%. According to the disclosure, there is a correlation between the Cube orientation accumulation ratio and the bending workability, and by controlling this, a copper alloy sheet material having excellent bending workability and excellent strength can be obtained.

[0006] Further, Patent Document 3 (JP2015-190044A) discloses that, at the stage before finish cold rolling, by controlling the ratio of the maximum side average crystal grain size / average grain size to be smaller than a certain level, and by reducing the number density of coarse second phase particles, the level of the bending workability of the copper alloy sheet material can be improved and variations can be reduced. Moreover, Patent Document 4 (JP2004-052008A) discloses a titanium copper alloy material comprising Ti of 1.0 to 5.0 mass% and the rest consisting of copper and inevitable impurities, characterized in that the value of the ratio of (the deviation of crystal grain size) / (the average crystal grain size) is 0.60 or less, and the mechanical properties such as bending workability and stress relaxation property of the titanium copper alloy material are uniform and good.

Citation List

[Patent Document]

[0007] 

[Patent Document 1] JP2013-100586A

[Patent Document 2] WO2012/029717

[Patent Document 3] JP2015-190044A

[Patent Document 4] JP2004-052008A

[0008] US2010/0139822 and EP A 2196548 each propose a Cu-Ti-based copper alloy sheet material and method of manufacturing same.

[Summary of Invention]

[Technical Problem to Be Solved]

[0009] Meanwhile, for the purpose of ensure clicking feeling during mounting, some of the materials for signal terminals are subjected to a beating process on both sides of the terminal in advance so as to reduce the plate thickness and then subjected to a bending process as before. At this time, the problem is that, since processing strain is introduced due to the beating process, when compared with the state in which the beating process is not conducted, the bending workability is impaired. For this reason, maintaining bending workability even when a beating process is conducted, is considered a problem. Although the inventions described in Patent Documents 1 to 4 have certain effects in improving the bending workability, in order to respond to the requirement of bending workability of titanium copper for electronic components to which beating process is applied, further improvement is desired.

[0010] Therefore, it is an object of present invention to improve bending workability of titanium copper for electronic components, and to provide a titanium copper for electronic components, which has excellent bending workability even when subjected to beating process, and to provide a method for manufacturing the same.

[Solution to Problem]

[0011] In order to solve the above technical problem, the inventors of the present invention conducted extensive research and discovered findings that, in order to improve the bending workability of titanium copper for electronic components to which beating process is applied, it is important to simultaneously control its work-hardening exponent, and the relation of the X-ray diffraction integrated intensity I {200} from the {200} crystal face on the surface of the titanium copper and the X-ray diffraction integrated intensity I₀ {200} of a pure copper standard powder.

[0012] Besides, the inventors also discovered finding that, to realize the control described above, when manufacturing a titanium copper by hot rolling an ingot of titanium copper, followed by a step of cold rolling and a final solution heat treatment, it is necessary to make the minimum working ratio per pass and the total working degree in the step of cold rolling within a certain range, while setting the rate of temperature rise and the heating temperature in the step of final solution heat treatment in a certain rage.

[0013] The present invention is accomplished based on the above findings.

[0014] Accordingly, the present invention is described as below:

(1) A titanium copper, comprising 2.0 to 4.5 mass% of Ti, and at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg, and Si in total of 0 to 0.5 mass% as a third element(s), and the rest consisting of copper and inevitable impurities,
wherein a work-hardening exponent is 0.05 to 0.25, and an X-ray diffraction integrated intensity I {200} from the {200} crystal face on the surface of the titanium copper and an X-ray diffraction integrated intensity I₀ {200} of a pure copper standard powder satisfy the following relation:
0.15 ≦ I {200} / I₀ {200} ≦ 0.70

(2) The titanium copper according to (1), wherein when a W bending test was performed in the Badway direction at r/t = 1.0 in accordance with JIS-H 3130 (2012) after a cold rolling with a working ratio of 10%, the average roughness Ra of the outer peripheral surface of the bent portion is 1.0 µm or less.

(3) The titanium copper according to (1) or (2), wherein in the crystal orientation analysis by EBSD measurement on the rolled surface, when an orientation difference of 5° or more is defined as a crystal grain boundary, an average crystal grain size is 2 to 30 µm.

(4) The titanium copper according to any one of (1) to (3), wherein when a tensile test is performed according to JIS-Z 2241 (2011), a 0.2% yield strength in a direction parallel to the rolling direction is 800 MPa or more.

(5) An electronic component, comprising the titanium copper according to any one of (1) to (4).

(6) A method for manufacturing the titanium copper according to any one of (1) to (4), the method comprising:

a step of hot rolling an ingot of titanium copper, the ingot comprising 2.0 to 4.5 mass% of Ti, and at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg, and Si in total of 0 to 0.5 mass% as a third element(s), and the rest consisting of copper and inevitable impurities;

a step of cold rolling; and subsequently

a step of final solution heat treatment;

wherein in the step of cold rolling before the step of final solution heat treatment, the minimum working ratio per pass is 10 to 30%, and when the total working degree η is indicated as η = In {(thickness before cold rolling) / (thickness after cold rolling)}, the η is 3.0 or more and less than 5.0; and

wherein in the step of final solution heat treatment, when the addition amount (mass%) of Ti is X, the final heating temperature (°C) is (52 × X + 610) to (52 × X + 680), the rate of temperature rise at 400 °C to the final heating temperature is 20 to 30 °C/s, and the duration of the final solution heat treatment is from 30 seconds to 10 minutes.

[Effect of Invention]

[0015] According to the present invention, bending workability of titanium copper for electronic components can be improved, and a titanium copper for electronic components, which has excellent bending workability even when subjected to beating process, as well as a method for manufacturing the same, can be provided.

[Description of Embodiments

(Ti Concentration)

[0016] In the titanium copper according to the present invention, the Ti concentration is set to 2.0 to 4.5 mass%. In the titanium copper, Ti is solidified in the Cu matrix by solution treatment, and fine precipitates are dispersed in the alloy by aging treatment, thereby increasing strength and conductivity.

[0017] When the Ti concentration is less than 2.0 mass%, precipitation of precipitates becomes insufficient and desired strength can not be obtained. When the Ti concentration exceeds 4.5% by mass, the processability is deteriorated, and the material is easily broken during rolling. Considering the balance of strength and workability, the preferable Ti concentration is 2.5 to 3.5 mass%.

(Third Element(s))

[0018] In the titanium copper according to the present invention, one or more third element(s) selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si can be contained, and thereby the strength can be further improved. However, when the total concentration of the third element(s) exceeds 0.5% by mass, the processability is deteriorated, and the material is easily broken during rolling. Therefore, these third elements can be contained in a total amount of 0 to 0.5 mass%. In view of the balance between strength and workability, it is preferable to contain one or more of the above elements in a total amount of 0.1 to 0.4 mass%. Further, for each additional element, Zr, P, B, V, Mg and Si in an amount of 0.01 to 0.15 mass%, Fe, Co, Ni, Cr, Mo, Nb and Mn in an amount of 0.01 to 0.3 mass%, and Zn in an amount of 0.1 to 0.5 mass%, may be contained.

(Work-Hardening Exponent (n value))

[0019] In a tensile test, when pulling a test piece to apply a load, in the plastic deformation range up to the maximum load point beyond the elastic limit, the test piece uniformly elongate (uniform elongation). In the plastic deformation region where this uniform elongation occurs, the relationship of the following formula (1) is established between the true stress σ_t and the true strain ε_t, which is called the n-th hardening rule.

[0020] Herein, in the formula (1), n is called work-hardening exponent (referred to as Hajime Sudo: Material Test Method, Uchida Rokakuho Publishing Co. LTD, (1976), p. 34), and takes the value 0 ≦ n ≦ 1.

[0021] For materials which follow the n-th hardening rule, since the true strain and the work-hardening exponent at the maximum load point of a stress-strain curve coincide with each other, in the present invention, the true strain at the maximum load point is set as the work-hardening exponent (n value) (referred to as Hajime Sudo: Material Test Method, Uchida Rokakuho Publishing Co. LTD, (1976), p. 35). Specifically, a tensile test in the rolling parallel direction can be carried out in accordance with JIS Z 2241 (2011) in the same manner as the measurement of 0.2% yield strength, which will be described hereinafter, to obtain a stress-strain curve. The true strain ε_t can be calculated by substituting the nominal strain ε at the maximum load point read from the obtained stress-strain curve into the following formula (2).

[0022] In order to obtain a titanium copper excellent in bending workability, it is important to set the n value within a predetermined range. Titanium copper is work hardened by beating, and the strength is increased. At this time, since the strength is in a trade-off relationship with the bending workability, the bending workability deteriorates due to the increase in strength. In order to suppress the increase in strength due to beating process, it is preferable to make the work-hardening index small. Specifically, the work-hardening exponent (n value) in the direction parallel to the rolling direction should be 0.05 to 0.25. The n value is preferably 0.08 to 0.22, more preferably 0.11 to 0.19.

(Crystal Orientation)

[0023] For the titanium copper according to the present invention, it is desirable that the X-ray diffraction integrated intensity I {200} from the {200} crystal face on the surface of the titanium copper and the X-ray diffraction integrated intensity I₀ {200} of a pure copper standard powder satisfy the relation: 0.15 ≦ I {200} / I₀ {200} ≦ 0.70. This is because if the ratio of I {200} / I₀ {200} is too large, the strain of each crystal grain becomes nonuniform and the bending workability deteriorates.

[0024] On the other hand, if the ratio of I {200} / I₀ (200) is too small, rolled texture develops and bending workability deteriorates.

[0025] Accordingly, the ratio of I {200} / I₀ (200) is preferably 0.25 or more and 0.60 or less, more preferably 0.30 or more and 0.50 or less.

[0026] Besides, the X-ray diffraction integrated intensity can be measured by using a predetermined X-ray diffraction apparatus.

(Bending Workability)

[0027] The titanium copper according to the present invention can have excellent bending workability. In one embodiment of the titanium copper according to the present invention, when a cold rolling with a working ratio of 10%, which simulates a beating process, is conducted, and subsequently a W bending test was performed in the Badway direction at r/t = 1.0 in accordance with JIS-H 3130 (2012) after the cold rolling, the average roughness Ra of the outer peripheral surface of the bent portion is 1.0 µm or less. The average roughness Ra is calculated according to JIS-B 0601 (2013). The fact that the average roughness of the bent portion is small even after the bending means that harmful cracks which may cause breakage are difficult to occur in the bent portion. Generally, the average roughness Ra of the surface of the titanium copper according to the present invention before the bending test is 0.2 µm or less.

[0028] The working ratio, which simulates a beating process, is based on the following equation. In the equation, T₀ is the thickness of the ingot before the cold rolling and T is the thickness of the ingot at the end of the cold rolling.

(Average Crystal Grain Size)

[0029] From the viewpoint of improving strength, bending workability and fatigue characteristics in a well-balanced manner, in one embodiment of titanium copper according to the present invention, it is preferable to control the average crystal grain size in the rolled surface within the range of 2 to 30 µm, more preferably in the range of 2 to 15 µm, and still more preferably in the range of 2 to 10 µm.

[0030] As with the average crystal grain size used to calculate the coefficient of variation of crystal grain size described above, the average crystal grain size means the average crystal grain size obtained by analyzing the crystal orientation in the EBSD (Electron Back Scatter Diffraction) measurement on the rolled surface, using analysis software attached to EBSD (e.g. OIM Analysis provided by TSL Solutions Co., Ltd.), wherein the average crystal grain size is calculated when an orientation difference of 5° or more is defined as a grain boundary.

(0.2% Yield Strength)

[0031] In some embodiments of the titanium copper according to the present invention, 0.2% yield strength in a direction parallel to the rolling direction may be 800 MPa or more. The 0.2% yield strength of titanium copper according to the present invention may be 850 MPa or more in a preferred embodiment, 900 MPa or more in a further preferred embodiment, and 950 MPa or more in a further preferred embodiment.

[0032] The upper limit of the 0.2% yield strength is not particularly restricted from the viewpoint of the strength intended by the present invention, but since it is troublesome and expensive, the 0.2% yield strength of titanium copper according to the present invention is generally 1300 MPa or less, typically 1200 MPa or less, more typically 1100 MPa or less.

[0033] In the present invention, the 0.2% yield strength in the direction parallel to the rolling direction is measured in accordance with JIS-Z 2241 (2011) (method for metal material tensile test).

(Thickness of Titanium Copper)

[0034] In one embodiment of titanium copper according to the present invention, the thickness can be 1.0 mm or less. In a typical embodiment, the thickness can be 0.02 to 0.8 mm, and in an more typical embodiment, the thickness can be 0.05 to 0.5 mm.

(Application)

[0035] Titanium copper according to the present invention can be processed into various copper elongation products such as plates, strips, pipes, rods and wires. The titanium copper according to the present invention is preferably used as a conductive material or a spring material in electronic components such as a switch, a connector, an autofocus camera module, a jack, a terminal (in particular, a battery terminal), a relay and the like, although its application is not limited. These electronic components can be used, for example, as in-vehicle parts or parts for electrical and electronic equipment.

(Manufacturing Method)

[0036] Hereinafter, preferable production examples of the titanium copper according to the present invention will be sequentially described for each step.

<Preparation of Ingot>

[0037] Preparation of ingot by melting and casting is basically carried out in vacuum or in an inert gas atmosphere. If undissolved residues of the added element(s) is present during dissolution, it does not work effectively for improving the strength. Therefore, in order to eliminate undissolved residues, for third elements having a high melting point such as Fe or Cr, after add the element, it is necessary to sufficiently stir it, and to maintain a certain period of time. On the other hand, since Ti is relatively soluble in Cu, it may be added after dissolution of the third element(s). Therefore, it is desirable to at first add one or more elements selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si in total of 0 to 0. 5 mass%, and then add Ti to a concentration of 2.0 to 4.5 mass%, so as to produce an ingot.

<Homogenization Annealing and Hot Rolling>

[0038] Since solidifying segregation and crystallization that occurred at the time of preparation of ingot are coarse, it is desirable to solidify them in the matrix to make them smaller, and more desirable to eliminate them as much as possible by homogenization annealing. This is because it is effective in preventing bending cracks. Specifically, after the ingot preparation process, it is preferable to perform homogenization annealing by heating to 900 to 970 °C and keeping for 3 to 24 hours, and then to perform hot rolling. In order to prevent liquid metal brittleness, it is preferable to set the temperature to 960 °C or less before and during the hot rolling, and to set the temperature to 900 °C or more during passes from the original thickness to the total reduction rate of 90%.

<Cold Rolling and Annealing>

[0039] After the hot rolling, cold rolling is performed. The working ratio of the cold rolling is typically 30% or more.

[0040] Subsequently, annealing can then be carried out. Here, the annealing conditions are typically 900 ° C. and 1 to 5 minutes. The cold rolling and the annealing can be repeated as necessary.

<First Solution Heat Treatment>

[0041] After appropriately repeating the cold rolling and the annealing, it is preferable to perform a first solution heat treatment. Here, the reason for preliminarily performing solution heat treatment is to reduce the burden on the final solution treatment. That is, in the final solution heat treatment, since the second phase particles are already solutionized, heat treatment for solid solution of the second phase particles is not necessary, and it is only necessary to maintain this state and further cause recrystallization, so that a slight heat treatment is sufficient. Specifically, the first solution heat treatment may be performed at a heating temperature of 850 to 900 °C for 2 to 10 minutes. It is also preferable to make the heating rate and the cooling rate at that time as high as possible and to prevent precipitation of the second phase particles during this process. Note that the first solution heat treatment may not be performed.

intermediate rolling>

[0042] The area ratio of the Cube orientation and the coefficient of variation of the crystal grain size are greatly affected by recrystallization in the final solution heat treatment. Since the driving force of recrystallization is the strain introduced by intermediate rolling which is the previous process, it becomes important to control the minimum working ratio per pass and the total working degree. Here, it is necessary to set the minimum working ratio per pass to 10 to 30%, and when the total working degree η is indicated as η = In {(thickness before cold rolling) / (thickness after cold rolling)}, it is necessary to set the η to 3.0 or more and less than 5.0.

[0043] When the minimum working ratio per pass is less than 10%, it becomes difficult to control the area ratio of I {200} / I₀ {200} of finally obtained titanium copper to 0.70 or less, whereas if the minimum working ratio per pass exceeds 30%, the material breaks and the production becomes difficult. From this viewpoint, the minimum working ratio per pass is preferably 13 to 27%, more preferably 16 to 24%.

[0044] Further, when the total working degree η is less than 3.0, it becomes difficult to control the ratio of I {200} / I₀ {200} of finally obtained titanium copper to 0.15 or more, whereas when the total processing degree η is 5 .0 or more, it also becomes difficult to control the area ratio of I {200} / I₀ {200} of finally obtained titanium copper to 0.70 or less. From this viewpoint, the total working degree η is preferably 3.3 to 4.7, more preferably 3.6 to 4.4.

[0045] The working ratio per pass can be obtained from the following equation. In the equation, T₀ is the thickness of the ingot before the cold rolling and T is the thickness of the ingot at the end of the cold rolling.

<Final Solution Heat Treatment>

[0046] In the final solution heat treatment, it is desirable to completely dissolve the precipitates, but when heated to a high temperature until precipitates are completely eliminated, the crystal grains tend to coarsen, so the heating temperature is set close to the solid solubility limit of the second phase particle composition. Specifically, when the addition amount (mass%) of Ti is X, the heating temperature (° C.) is set to (52 × X + 610) to (52 × X + 680). When the heating temperature is lower than 52 × X + 610, recrystallization becomes insufficient, and when the heating temperature exceeds 52 × X + 680, the crystal grain size becomes coarse, and the bending workability of finally obtained titanium copper is remarkably deteriorated. Here, it is necessary to control the rate of temperature rise at 400 °C or higher to 20 to 30 °C/s. In the temperature range of 400 °C or higher, when the rate of temperature rise is less than 20 °C/s, precipitation occurs during the temperature rising process because the heating time is prolonged, and when the rate of temperature rise exceeds 30 °C/s, As the time is shortened, it becomes an unstable heat treatment, and as a result, it becomes difficult to control the coefficient of variation of the crystal grain size of finally obtained titanium copper to 45% or less.

[0047] In addition, shorter heating time in the final solution heat treatment can suppress coarsening of crystal grains. Thus the heating time is, for example, 30 seconds to 10 minutes, and typically 1 minute to 8 minutes. During this period, even if second phase particles are generated, as long as they are finely and uniformly dispersed, they are almost harmless to strength and bending workability. However, coarse particles tend to grow further in the final aging treatment, so if second phase particles are generated during this period, they should be made as few as possible and should be made as small as possible.

<Final Cold Rolling>

[0048] The final solution heat treatment is followed by the final cold rolling. Although the strength can be increased by the final cold rolling, in order to obtain bending workability as intended in the present invention, it is desirable set to the reduction ratio to 5 to 50%, preferably to 20 to 40%.

<Aging treatment>

[0049] The final cold rolling is followed by aging treatment. It is preferable to heat at a material temperature of 300 to 500 °C for 1 to 50 hours, more preferably at a material temperature of 350 to 450 °C for 10 to 30 hours. The aging treatment is preferably performed in an inert atmosphere such as Ar, N₂, H₂ or the like in order to suppress the generation of the oxide film.

[0050] Summarizing the above, in one embodiment of the method for manufacturing titanium copper according to the present invention, the method comprises:

a step of preparing an ingot of titanium copper, the ingot comprising 2.0 to 4.5 mass% of Ti, and at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg, and Si in total of 0 to 0.5 mass% as a third element(s), and the rest consisting of copper and inevitable impurities;

a step of hot rolling the ingot;

a step of cold rolling, wherein the minimum working ratio per pass is 10 to 30%, and when the total working degree η is indicated as η = In {(thickness before cold rolling) / (thickness after cold rolling)}, the η is 3.0 or more and less than 5.0; and

a step of final solution heat treatment, wherein when the addition amount (mass%) of Ti is X, the heating temperature (°C) is (52 × X + 610) to (52 × X + 680), and the rate of temperature rise at 400 °C or higher is 20 to 30 °C/s.

[0051] Those skilled in the art will appreciate that steps such as grinding, polishing, shot-blast acid washing and the like for removing oxide scales on the surface can be appropriately performed between the above steps.

[Examples]

[0052] Hereinafter, the present invention will be specifically described using examples and comparative examples. However, The descriptions of the following examples and comparative examples are merely specific examples for facilitating understanding of the technical contents of the present invention and the technical scope of the present invention is not limited by these specific examples.

[0053] Alloys containing the alloy components shown in Table 1 and the rest consisting of copper and inevitable impurities were used as an experimental materials and effects of the alloy components, the production conditions for cold rolling and subsequent final solution heat treatment on the 0.2% yield strength, the work-hardening exponent, the ratio of I {200} / I₀ {200}, and the bending workability after rolling were investigated.

[0054]  First, 2.5 kg of electrolytic copper was dissolved in a vacuum melting furnace, and third element(s) was added at the mixing ratio shown in Table 1, and then Ti of the compounding ratio shown in the same table was added. After carefully considering the retention time after addition so that there is no residue of added elements, these were injected into a mold in Ar atmosphere to produce ingots of about 2 kg each.

[0055] After homogenizing annealing to the ingot at 950 °C for 3 hours, hot rolling was performed at 900 to 950 °C to obtain a hot rolled sheet having a thickness of 15 mm. After descaling by surface milling, cold rolling and annealing were repeated to obtain strip thicknesses (0.3 to 3.3 mm), and a first solution heat treatment was performed on the stripes. The conditions of the first solution heat treatment were heating at 850 °C for 10 minutes and then water cooling. Subsequently, intermediate cold rolling was carried out under the conditions shown in Table 1, then inserted into an annealing furnace which is capable of rapid heating, and the final solution treatment was performed, followed by water cooling. The heating conditions at this time were set as shown in Table 1. Then, after descaling by acid washing, final cold rolling with a reduction ratio of 25% was performed to obtain a plate thickness of 0.1 mm and finally subjected to aging treatment at 400 °C × 20 hours to obtain test pieces of the Examples and Comparative Examples Respectively.

[0056] The following tests were conducted on the prepared test pieces.

(0.2% yield strength)

[0057] JIS 13B test piece was prepared and the 0.2% yield strength in the direction parallel to the rolling direction was measured using a tensile tester according to the above measuring method.

(Average crystal grain size)

[0058] After polishing the plate surface (rolled surface) of each test piece and etching it, in the analysis of crystal orientation by EBSD (Electron Back Scatter Diffraction) measurement, using analysis software attached to EBSD (eg, OIM Analysis provided by TSL Solutions Co., Ltd.), the average crystal grain size in the case where the orientation difference of 5° or more was defined as a grain boundary was measured.

(Work-hardening exponent (n value))

[0059] A tensile test in a direction parallel to the rolling direction was performed to obtain a stress-strain curve, and the n value was obtained by the above-described method.

(Crystal orientation)

[0060] With respect to each test piece, using the X-ray diffraction apparatus of RINT 2500 manufactured by Rigaku Corporation, a diffraction intensity curve of the surface was obtained under the following measurement conditions to obtain the integrated intensity I of {200} crystal plane, {220} crystal plane, and {311} crystal plane, respectively. And then, (I {220} + I {311}) / I {200} was calculated. As to the pure copper standard powder sample, the integrated intensity I of the {200} crystal face was measured under the same measurement conditions, and I {200} / I₀ {200} was calculated.

▪ Target: Co bulb

▪ Tube voltage: 30 kV

▪ Tube current: 100 mA

▪ Scan speed: 5° / min

▪ Sampling width: 0.02 °

▪ Measurement range (2θ): 5° to 150°

(Bendability after rolling)

[0061] A cold rolling with a working ratio of 10%, which simulates a beating process, was conducted, and subsequently a W bending test was performed in the Badway direction at r/t = 1.0 in accordance with JIS-H 3130 (2012) after the cold rolling. The outer peripheral surface of the bent portion of this test piece was observed. For the observation method, the outer peripheral surface of the bent portion was photographed using a confocal microscope HD100 manufactured by Lasertec Corporation, and the average roughness Ra (according to JIS-B 0601: 2013) was measured using the attached software and compared. When the surface of the sample before bending was observed with a confocal microscope, irregularities were not confirmed, and the average roughness Ra was 0.2 µm or less in each case. A case where the surface average roughness Ra after bending was 1.0 µm or less was evaluated as "OK" and a case where Ra was more than 1.0 µm was evaluated as "NG".

[Table 1]

	Conditions for production						Final characteristics
	Component (mass%)		Cold rolling before final solution heat treatment		Final solution heat treatment
	Ti	Third element	minimum working ratio per pass(%)	total working degree (η)	rate of temperature rise at 400 °C or higher (°C/s)	heating temperature (°C)	0.2% yield strength (MPa)	average crystal grain size (µm)	coefficient of variation of crystal grain size (%)	Area ratio of Cube orientation (%)	bendability after rolling
Example 1	3.1	-	18	4	24	790	917	15	0	0.4	OK
Example 2	3.1	-	12	4	24	790	925	13	0	0.6	OK
Example 3	3.1	-	28	4	24	790	921	13	0	0.2	OK
Example 4	3.1	-	18	3.2	24	790	920	12	0	0.2	OK
Example 5	3.1	-	18	4.8	24	790	924	11	0	0.6	OK
Example 6	3.1	-	18	4	21	790	915	17	0	0.4	OK
Example 7	3.1	-	18	4	29	790	910	16	0	0.4	OK
Example 8	3.1	-	18	4	24	780	926	10	0	0.3	OK
Example 9	3.1	-	18	4	24	830	904	27	0	0.4	OK
Example 10	2.0	-	18	4	24	740	812	18	0	0.5	OK
Example 11	4.5	-	18	4	24	870	1054	14	0	0.2	OK
Example 12	3.1	0.2Fe	22	3.4	24	790	963	5	0	0.3	OK
Example 13	3.1	0.2Mn-0.05B	24	3.4	22	800	930	8	0	0.2	OK
Example 14	3.1	0.3Zn-0.1 Ni-0.05Zr	12	4.6	24	780	925	7	0	0.7	OK
Example 15	3.1	0.1Co-0.1Nb	15	4.2	24	820	933	6	0	0.5	OK
Example 16	3.1	0.1V-0.1Mg	14	4.2	26	820	931	21	0	0.5	OK
Example 17	3.1	0.3Mo-0.05Cr	26	3.4	26	820	924	15	0	0.3	OK
Example 18	3.1	0.1Si-0.05P	20	3.6	22	790	923	16	0	0.3	OK
Comparative Example 1	3.1	-	7	4	24	790	916	17	0	0.8	NG
Comparative Example 2	3.1	-	(35)	Not manufacturable			-	-	-	-	-
Comparative Example 3	3.1	-	18	2.8	24	790	926	13	0	0.1	NG
Comparative Example 4	3.1	-	18	5.2	24	790	918	13	0	0.8	NG
Comparative Example 5	3.1	-	18	4	18	790	921	15	0	0.4	NG
Comparative Example 6	3.1	-	18	4	32	790	927	14	0	0.4	NG
Comparative Example 7	3.1	-	18	4	24	760	964	Unrecrystallized	0.03	0.1	NG
Comparative Example 8	3.1	-	18	4	24	840	845	40	0.28	0.5	NG
Comparative Example 9	3.1	0.3Fe-0.3Ni	Not manufacturable				-	-	-	-	-
Comparative Example 10	1.5	-	18	4	24	720	745	24	0.23	1.0	NG
Comparative Example 11	5.0	-	Not manufacturable				-	-	-	-	-
Comparative Example 12	3.1	-	6	4.0	15	790	926	14	0.15	0.79	NG

(Discussions)

[0062] In Examples 1 to 18, since the work-hardening exponent and the ratio of I {200} / I₀ {200} were all within the range of the present invention, the bending workability is excellent. Further, the average crystal grain size was 2 to 30 µm, and the 0.2% yield strength was 800 MPa or more.

[0063] On the other hand, in Comparative Example 1, since the minimum working ratio per pass was too low, the ratio of I {200} / I₀ {200} was outside the range of the present invention, and the bending workability was inferior to the Examples.

[0064] In Comparative Example 2, the minimum working ratio per pass was too high, and as a result the material broke and it was impossible to continue production.

[0065] Since the total working degree of Comparative Example 3 was too low, the ratio of I {200} / I₀ {200} was smaller than the lower limit of the present invention. Therefore, the bending workability was inferior to the Examples.

[0066] Since the total working degree of Comparative Example 4 was too high, the ratio of I {200} / I₀ {200} was larger than the upper limit of the present invention. Therefore, the bending workability was inferior to the Examples.

[0067] Since the rate of temperature rise in Comparative Example 5 at 400 °C or higher too slow, the work-hardening exponent was smaller than the lower limit of the present invention. Therefore, the bending workability was inferior to the Examples.

[0068] Since the rate of temperature rise in Comparative Example 6 at 400 °C or higher too fast, the work-hardening exponent was larger than the upper limit of the present invention. Therefore, the bending workability was inferior to the Examples.

[0069] Since the heating temperature in Comparative Example 7 was too low, recrystallization was insufficient, and titanium copper intended for the present invention could not be produced.

[0070] Since the heating temperature in Comparative Example 8 was too high, the work-hardening exponent exceeded the upper limit of the present invention. Therefore, the bending workability was inferior to the Examples.

[0071] Since the third element(s) added to Comparative Example 9 was too much, the material cracked during rolling, and titanium copper intended for the present invention could not be produced.

[0072] Since the amount of Ti added to Comparative Example 10 was too small, the ratio of I {200} / I₀ {200} exceeded the upper limit of the present invention. Therefore, the bending workability was inferior to the Examples.

[0073] Since the amount of Ti added to Comparative Example 11 was too large, the material cracked during rolling, and titanium copper intended for the present invention could not be produced.

[0074] In the Comparative Example 12, since the minimum working ratio per pass is lower than 10% and the rate of temperature rise at 400 °C or higher is lower than 20 °C/min, the ratio of I {200} / I₀ {200} exceeded the upper limit of the present invention. Therefore, the bending workability was inferior to the Examples.

Claims

1. A titanium copper, comprising 2.0 to 4.5 mass% of Ti, and at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg, and Si in total of 0 to 0.5 mass% as a third element(s), and the rest consisting of copper and inevitable impurities,
wherein a work-hardening exponent is 0.05 to 0.25, and an X-ray diffraction integrated intensity I {200} from the {200} crystal face on the surface of the titanium copper and an X-ray diffraction integrated intensity I₀ {200} of a pure copper standard powder satisfy the following relation:
0.15 ≦ I {200} / I₀ {200} ≦ 0.70

2. The titanium copper according to claim 1, wherein when a W bending test was performed in the Badway direction at r/t = 1.0 in accordance with JIS-H 3130 (2012) after a cold rolling with a working ratio of 10%, the average roughness Ra of the outer peripheral surface of the bent portion is 1.0 µm or less.

3. The titanium copper according to claim 1 or 2, wherein in the crystal orientation analysis by EBSD measurement on the rolled surface, when an orientation difference of 5° or more is defined as a crystal grain boundary, an average crystal grain size is 2 to 30 µm.

4. The titanium copper according to any one of claims 1 to 3, wherein when a tensile test is performed according to JIS-Z 2241 (2011), a 0.2% yield strength in a direction parallel to the rolling direction is 800 MPa or more.

5. An electronic component, comprising the titanium copper according to any one of claims 1 to 4.

6. A method for manufacturing the titanium copper according to any one of claims 1 to 4, the method comprising:

a step of hot rolling an ingot of titanium copper, the ingot comprising 2.0 to 4.5 mass% of Ti, and at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg, and Si in total of 0 to 0.5 mass% as a third element(s), and the rest consisting of copper and inevitable impurities;

a step of cold rolling; and subsequently

a step of final solution heat treatment;

wherein in the step of cold rolling before the step of final solution heat treatment, the minimum working ratio per pass is 10 to 30%, and when the total working degree η is indicated as η = In {(thickness before cold rolling) / (thickness after cold rolling)}, the η is 3.0 or more and less than 5.0; and

wherein in the step of final solution heat treatment, when the addition amount (mass%) of Ti is X, the final heating temperature (°C) is (52 × X + 610) to (52 × X + 680), the rate of temperature rise at 400 °C to the final heating temperature is 20 to 30 °C/s, and the duration of the final solution heat treatment is from 30 seconds to 10 minutes.

Ansprüche

1. Titankupfer, das 2,0 bis 4,5 Massen-% Ti und zumindest ein Element, das aus der aus Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg und Si bestehenden Gruppe ausgewählt ist, mit insgesamt 0 bis 0,5 Massen-% als drittes Element bzw. dritte Elemente umfasst und wobei der Rest aus Kupfer und unvermeidbaren Verunreinigungen besteht,
wobei ein Kaltverfestigungsexponent 0,05 bis 0,25 beträgt und eine integrierte Intensität der Röntgenbeugung I {200} der {200}-Kristallfläche auf der Oberfläche des Titankupfers und eine integrierte Intensität der Röntgenbeugung I₀ {200} eines reinen Kupferstandardpulvers folgendes Verhältnis aufweisen:
0,15 ≦ I {200} / I₀ {200} ≦ 0,70.

2. Titankupfer nach Anspruch 1, wobei bei Durchführung eines W-Biegetests in Badway-Richtung bei r/t = 1,0 gemäß JIS-H 3130 (2012) nach einem Kaltwalzen bei einem Bearbeitungsverhältnis von 10 % die mittlere Rauheit Ra der äußeren Umfangsfläche des gebogenen Abschnitts 1,0 µm oder weniger beträgt.

3. Titankupfer nach Anspruch 1 oder 2, wobei in der Kristallorientierungsanalyse mittels EBSD-Messung auf der gewalzten Oberfläche, wenn eine Orientierungsdifferenz von 5° oder mehr als Kristallkorngrenze definiert ist, eine mittlere Kristallkorngröße 2 bis 30 µm beträgt.

4. Titankupfer nach einem der Ansprüche 1 bis 3, wobei bei der Durchführung einer Zugprüfung gemäß JIS-Z 2241 (2011) eine Streckgrenze von 0,2 % in einer zur Walzrichtung parallelen Richtung 800 MPa oder mehr beträgt.

5. Elektronische Komponente, die ein Titankupfer nach einem der Ansprüche 1 bis 4 umfasst.

6. Verfahren zur Herstellung eines Titankupfers nach einem der Ansprüche 1 bis 4, wobei das Verfahren Folgendes umfasst:

einen Schritt des Warmwalzens eines Titankupferrohlings, wobei der Rohling 2,0 bis 4,5 Massen-% Ti und zumindest ein Element, das aus der aus Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg und Si bestehenden Gruppe ausgewählt ist, mit insgesamt 0 bis 0,5 Massen-% als drittes Element bzw. dritte Elemente umfasst und der Rest aus Kupfer und unvermeidbaren Verunreinigungen besteht;

einen Schritt des Kaltwalzens; und anschließend

einen Schritt des Wärmebehandelns der finalen Lösung;

wobei in dem Schritt des Kaltwalzens vor dem Schritt des Wärmebehandelns der finalen Lösung das minimale Bearbeitungsverhältnis pro Durchlauf 10 bis 30 % beträgt und, wenn der Gesamtbearbeitungsgrad η als η = In {(Dicke vor dem Kaltwalzen) / (Dicke nach dem Kaltwalzen)} angegeben wird, η gleich 3,0 oder mehr und weniger als 5,0 ist; und

wobei in dem Schritt des Wärmebehandelns der finalen Lösung, wenn die Zugabemenge (Massen-%) von Ti X ist, die endgültige Heiztemperatur (°C) gleich (52 x X + 610) bis (52 x X + 680) ist und die Rate des Temperaturanstiegs bei 400 °C bis zur endgültigen Heiztemperatur 20 bis 30 °C/s beträgt und die Dauer des Wärmebehandelns der finalen Lösung 30 Sekunden bis 10 Minuten beträgt.

Revendications

1. Cuivre au titane comprenant 2,0 à 4,5 % en masse de Ti, et au moins un élément choisi dans le groupe constitué par Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg et Si à raison de 0 à 0,5 % en masse au total en tant qu'élément(s) tiers, le reste étant constitué de cuivre et d'impuretés inévitables,
dans lequel le coefficient d'écrouissage est de 0,05 à 0,25, et l'intensité intégrée de diffraction des rayons X I {200} depuis la face cristalline {200} sur la surface du cuivre au titane et l'intensité intégrée de diffraction des rayons X I₀ {200} d'une poudre standard de cuivre pur satisfont à la relation suivante :
0,15 ≤ I {200} / I₀ {200} ≦ 0,70

2. Cuivre au titane selon la revendication 1, dans lequel, quand un test de pliage W est effectué dans la mauvaise direction à r/t = 1,0 conformément à la norme JIS-H 3130 (2012) après un laminage à froid à un taux d'usinage de 10 %, la rugosité moyenne Ra de la surface périphérique extérieure de la partie pliée est de 1,0 µm ou moins.

3. Cuivre au titane selon la revendication 1 ou 2, dans lequel, dans une analyse d'orientation cristalline par mesure EBSD sur la surface laminée, quand une différence d'orientation de 5° ou plus est définie comme étant l'interface cristalline, la taille moyenne des cristaux est de 2 à 30 µm.

4. Cuivre au titane selon l'une quelconque des revendications 1 à 3, dans lequel, quand un test de traction est effectué conformément à la norme JIS-Z 2241 (2011), la limite d'élasticité à 0,2 % dans une direction parallèle à la direction de laminage est de 800 MPa ou plus.

5. Composant électronique comprenant le cuivre au titane de l'une quelconque des revendications 1 à 4.

6. Procédé de fabrication du cuivre au titane de l'une quelconque des revendications 1 à 4, le procédé comprenant :

une étape de laminage à chaud d'un lingot de cuivre au titane, le lingot comprenant 2,0 à 4,5 % en masse de Ti, et au moins un élément choisi dans le groupe constitué par Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg et Si à raison de 0 à 0,5 % en masse au total en tant qu'élément(s) tiers, le reste étant constitué de cuivre et d'impuretés inévitables ;

une étape de laminage à froid ; et ensuite

une étape de traitement thermique final de mise en solution ;

dans lequel, dans l'étape de laminage à froid avant l'étape de traitement thermique final de mise en solution, le taux d'usinage minimal par passage est de 10 à 30 %, et quand le degré d'usinage total η est représenté par η = In {(épaisseur avant laminage à froid) / (épaisseur après laminage à froid)}, η vaut 3,0 ou plus et moins de 5,0 ; et

dans lequel, dans l'étape de traitement thermique final de mise en solution, quand la quantité ajoutée (% en masse) de Ti est X, la température finale de chauffage (°C) est de (52 × X + 610) à (52 × X + 680), la vitesse de montée en température de 400°C à la température finale de chauffage est de 20 à 30°C/s, et la durée du traitement thermique final de mise en solution est de 30 secondes à 10 minutes.